The present invention relates to an organopolysiloxane elastomer which is prepared through an SiH olefin addition reaction and more particularly the present invention relates to an organopolysiloxane elastomer which is prepared through an SiH olefin addition in the presence of a platinum catalyst to result in an elastomer with high tensile strength, good elongation and high tear.
At the present time, there has been produced various silicone gels which are used for orthopedic devices or prosthetic devices. It has been found highly desirable to encase such orthopedic gels in a film of material so that the resulting gel could be used as an orthopedic device or prosthetic device. It was desired that the film of material have a high tensile strength, a good elongation and a high tear so that the film even in small thicknesses could not be punctured accidentally and the gel allowed to leak out requiring frequent repairs of the orthopedic or prosthetic device.
One attempt to provide such a film was the use of heat vulcanizable silicone rubber compositions. Although such films could possibly be prepared through the use of heat vulcanizable silicone rubber compositions it was found that such heat vulcanizable silicone rubber compositions were difficult to work with and especially in preparing films of small thicknesses such as 6 to 25 mils. In addition, heat cured rubber has low elongations.
Other organopolysiloxane compositions such as room temperature vulcanizable silicone rubber compositions were tried to prepare such films with the same difficulties as was experienced with heat vulcanizable silicone rubber compositions.
In addition, traditional siH-olefin addition reaction products were tried to produce the required films or coatings. However, such traditional SiH olefin addition elastomeric compositions were found not to have as high a tensile as would be desired and more specifically were found to have a low elongation and a low tear.
Accordingly, it was highly desirable to discover a silicone rubber composition which would cure quickly, if desired, at elevated temperatures and would require no post baking as is traditional with heat vulcanizable silicone rubber compositions.
It was also desirable to prepare a silicone rubber composition which could be injection molded. Most silicone rubber compositions and particularly heat vulcanizable silicone rubber compositions because of their high viscosity are very difficult to injection mold and require excessively high pressure such as, 40,000 psi and even higher. In addition, such heat vulcanizable silicone rubber compositions are difficult to injection mold so as to form intricate parts, and they require special molds that are to be used in the injection molding as well as long times to cure at elevated temperatures.
Accordingly, it is one object of the present invention to provide for an SiH olefin addition elastomeric silicone rubber composition which in the cured state has a combination of high tensile strength, high elongation and high tear compared to that of the best heat vulcanizable silicone rubber compositions.
In addition, it is another object of the present invention to provide for an SiH olefin addition silicone rubber composition that can be used to form films or coatings of exceptionally high strength, high elongation and high tear, which coatings and films are easy to form and can be cured either at room temperature or at an exceedingly fast rate at elevated temperatures.
It is still an additional object of the present invention to provide for an SiH olefin addition silicone rubber composition which is especially suited for low pressure injection molding to form any type of parts and which composition can be cured at a very fast rate at elevated temperatures.
These and other objects of the present invention are accomplished by means of the composition set forth hereinbelow.